Pervious concrete composition

Abstract

The invention relates to pervious concrete compositions containing hydraulic binder, filler and polymer, characterized in that the polymer present is a vinyl acetate-ethylene-copolymer having a glass transition temperature Tg of ≦20° C.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application is the national phase filing of international patent application No. PCT / EP2009 / 066283, filed 3 Dec. 2009, and claims priority of German patent application number 10 2008 044 395.6, filed 5 Dec. 2008, the entireties of which applications are incorporated herein by reference.FIELD OF THE INVENTION[0002]The invention relates to a pervious concrete composition containing cement, filler and polymer, a process for the production of the pervious concrete composition, and the use of the pervious concrete composition.BACKGROUND OF THE INVENTION[0003]Pervious concrete is a no-fines, cavity-rich concrete. The cavity volume of pervious concrete is between 10 and 35 vol. %, preferably 20 to 25 vol. %. The no-fines pores arise through the use of fillers of narrowly limited particle size group, wherein usually only a single particle size group is used (uniform grain size, such as for example 5 / 8 mm chippings) and with almost complete r...

AI Technical Summary

Benefits of technology

[0009]The problem therefore existed of improving the pervious concrete composition sufficiently that crack formation and grain escape are minimized, without the mechanical strength suffering thereby. In addition, it should be possible to dispense with the application of a surface treatment layer. Surprisingly, it was found that the vinyl acetate ethylene copolymers according to the invention increase the bending tensile strength and hence the flexibility of the pervious concrete under various climatic conditions (both at cold and also at hot temperatures) compared to the state of the art.

Problems solved by technology

The longevity of these pavement systems is limited owing to the formation of cracks and particle escape.

However, this system does not meet the requirements for the durability of water-permeable and noise-absorbing road surfaces, since the water-soluble macromolecular substances can be washed out by rainwater and pure polyvinyl acetate becomes brittle at low temperatures of <10° C.

The costly incorporation of the whole system in several layers, and the use of polyurethane or epoxide adhesives as binders, without cheaper mineral binders such as cement, make the floor covering expensive and not widely utilizable.

Moreover, polyurethane and epoxide adhesives are not ecologically problem-free.

The styrene-acrylate copolymers used should preferably have a high minimum film-forming temperature (MFT) in the range from 35° C. to 50° C. Such styrene copolymers are rigid polymers, which do not sufficiently increase the flexibility of the open-pore concrete layer and have inadequate crack bridging properties.

Since rigid styrene acrylates of high MFT become brittle at low temperatures <10° C. and their performance is impaired, crack formation and grain escape occur in the uniform grain size concrete layer, resulting in poor durability, in particular after the winter period.

The structure has the disadvantage that a surface treatment layer is necessary to improve the wear of the pervious concrete layer and the skid resistance.

This surface treatment layer is applied in the form of a polymer-modified mortar which can partly seal off the pores of the pervious concrete layer which has an adverse effect on the noise-absorbing properties and the drainage of the open-pore structure.

Moreover, its application requires an additional working step, which adversely affects the economics.